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Lyme Disease: Wisconsin Data

Lyme disease is native to Wisconsin. Lyme disease and the ticks that carry it have spread from the northwestern part of the state to nearly all areas of the state over the past 30 years. This spread has caused more and more cases of the disease.

In 2020, Wisconsin had 3,076 estimated cases of Lyme disease. The average number of reported cases has more than doubled over the past 15 years.

The CDC (Centers for Disease Control and Prevention) monitors Lyme disease throughout the United States. It estimates the total number of cases is more than 10 times higher than what is reported. Wisconsin is one of the states reporting the highest number of cases. The actual number of Lyme disease cases in Wisconsin each year is likely to be much higher than reported.

Lyme disease is preventable and treatable. Learn more about Tick Bite Prevention.

Wisconsin map showing Lyme disease by county


Read about Treatment and Signs and Symptoms of Untreated Lyme Disease from the CDC.

The graphs below show statewide data for Lyme disease. For county-level data, see the Environmental Public Health Tracking: Lyme Disease.

For national data, visit the CDC webpage on Lyme Disease Data and Surveillance.

Borrelia burgdorferi data

This graph shows Wisconsin Lyme disease cases broken down by confirmed, probable, and estimated cases.

Lyme disease by year

In 2008, the surveillance case definition of Lyme disease changed to include probable cases of Lyme disease.

In 2012, the Division of Public Health modified the way it conducts Lyme disease surveillance. This helped address the increased burden of Lyme disease reporting on local or tribal health departments and medical care providers. The change introduced the need for estimated cases to account for cases that would have been reported through the surveillance system before 2012.

This incidence trend line of Lyme disease cases reflects what is shown in the bar graph above.

Lyme disease incidence per 100,000 by year

Most cases of Lyme disease occur during June and July. However, it’s possible to get Lyme disease whenever ticks are active. Ticks are active when temperatures are above freezing. It’s important to take steps toward Tick Bite Prevention when spending time outdoors.

Lyme disease by month

Lyme disease is most common in younger and older people. However, people of any age can become infected with Lyme disease.

Lyme disease by age group

Borrelia mayonii data

The bacterium Borrelia burgdorferi causes most cases of Lyme disease. However, Borrelia mayonii is a rare, newly emerging species. Borrelia mayonii also causes Lyme disease. It was first detected in 2013 in the Midwest, with 10 cases in Wisconsin residents from 2013 to 2021.

B. mayonii, Lyme disease cases by year

B. mayonii, Lyme disease cases by month

B. mayonii, Lyme disease cases by age group


Learn more about Lyme disease

Contact us

Questions about illnesses spread by ticks? We’re here to help.

Bureau of Communicable Diseases
Phone: 608-267-9003
Fax: 608-261-4976

Last revised January 6, 2023